What to do with old contacts on phone that aren't used anymore?

If you have or use a Google account, it's likely your contacts are backed up to https://contacts.google.com (I think Google has its own contacts app). This has a handy section called 'other contacts' which is where it automatically saves contacts you've hardly had anything to do with (i.e. if you only have an email address for them and no name - usually picked up automatically from Gmail). I just move old contacts to that section and they don't show on my phone.

If you don't want to keep these people in your contacts that means you never plan to talk to them again for all of your life. You even specifically said "WERE" planning on renting a house from him... ie NO LONGER CONSIDERING THAT. So why would you ever be "looking at his text messages" in the future? Simply delete his text messages!

If there are any you need to keep for legal purposes but they are several years old, you can transfer them to email or whagever your normally do for message conversations that you want to keep when you are switching phones but your previously-used phone is still capable of both turning on and looking at text messages. And if you want to keep the text messages because of friendship or relationship that you still might want to look at, then obviously you might need their number some day as well.

Your phone probably has a "Notes" field in your contacts details (screenshot from Oneplus phone on Android). Use it to add details about your contact like where you know them from/how you met.

Contacts

Smartphones have a Favorite contacts feature; marking all your current-in-your-life contacts as Favorite will allow you to have a smaller pruned list of people you regularly communicate with(the Favorites) but also let you keep a massive list of everyone's numbers ever(in the Contacts), and keeps all your text message conversations named but also that isn't cluttered up with every pizza shop, cab company and handy man you may have engaged once

Avoid putting people in your contacts with just a first name. If you don't know a last name out something descriptive such as Dave The Digger Driver or Dave From Next Door. You can edit the last name in later but you'll probably find you keep the more descriptive name. As a parent you might find yourself using the last name field to store the names of the children. I even find myself creating numberless contacts for people i see semi regularly in person

Messages

Android messages app has a facility for archiving messages; swipe left on a message thread or long press to select multiple threads to archive

iPhone doesn't have a really good way of archiving threads on-phone that I know of. Most solutions for it involve syncing the threads to a computer. The rise of competing messaging apps like WhatsApp, Signal, Telegram etc do offer ways to archive threads though

Although it would take time, you could prefix all your older contacts with the word "OLD". For example:

• First name "OLD Joe"
• Last name "Blow"

That way, you would keep the old contacts, but they would all be grouped together alphabetically (because they all start with "OLD") and you wouldn't mix them up with current / active contacts.

To group them together at the end of your contacts, prefix them with "zz":

• First name "zz Joe"
• Last name "Blow"

.

Note: As you can guess, this process will take a lot of time initially. But it would probably be worth it, organizationally. Also, if you start communicating with an "old" contact again, you can just remove that prefix from their name to put them "back in circulation" so to speak. Once a month your may want to review current contacts and see if any should be moved to "zz" or "OLD".